I really like the trebly guitar tone a la Under a Funeral Moon and Bathory's S/T. The problem is I have two guitar amps, Roland Microcube, and a Peavey JSX. I understand that the key is to boost the treble, but my Microcube has only a tone knob, it just doesn't get squeeky tones. The JSX has too much tube punch for a black metal tone.

For my own personal tone, yes. I'm a fan of "guitar > amp > cab", as far as rhythm guitar is concerned. However my tone is very far from black metal, and an EQ pedal would be a great way to reduce punch and bass from a sound.

Correct me if I'm wrong but don't both Immortal and Dimmu Borgir use bass in their guitar tone?

Immortal used to be trebly, now they are a thrash hybrid. And Dimmu Borgir is uhhhhh Dimmu Borgir.

they dont have too much Bass, they have more Mid.
and there is nothing wrong with Dimmu. the new stuff isnt that great, but Albums Like Enthrone Darkness Triumphant wich was a Gothic black metal masterpeice makes up for it 10 fold.

Well Nocturno Culto uses Gibsons, mainly a Les Paul Custom - the sound is either a practice amp or a distortion pedal straight into the desk (4-track). On Panzerfaust I'm sure hes using a practice amp on full tilt and it is a really good sound. One thing is for sure - you won't get the sound you are looking for using a high quality valve amp: also I think with the exception of Darkthrone and Mayhem (Euro also used a Les Paul) most of the early black metal bands used cheap guitars. Burzum and early Emperor used cheap strat copies, which you wouldn't normally use in metal. This was no doubt a result of them being kids and using beginners guitars they got for their birthdays....

Well Nocturno Culto uses Gibsons, mainly a Les Paul Custom - the sound is either a practice amp or a distortion pedal straight into the desk (4-track). On Panzerfaust I'm sure hes using a practice amp on full tilt and it is a really good sound. One thing is for sure - you won't get the sound you are looking for using a high quality valve amp: also I think with the exception of Darkthrone and Mayhem (Euro also used a Les Paul) most of the early black metal bands used cheap guitars. Burzum and early Emperor used cheap strat copies, which you wouldn't normally use in metal. This was no doubt a result of them being kids and using beginners guitars they got for their birthdays....

I'd imagine it wouldn't be hard to get a Deathcrush tone with my valve. I know Euronymous used a Les Paul and a Marshall JMP.

Forgot to mention though, your Peavey amp is a very, very different beast to the Marshall that Euro used - the tone is much more compressed in a way that none of the early 90's black metal was. However its still very possible to get a similar sound with a bit of tweaking!